Fear of a bot planet

Britain has the largest zombie PC population of any country on the planet, according to the latest Symantec Internet Security Threat Report.

The UK has more than a quarter (25.2 per cent) of all bots – virus-infected, zombie PCs under the control of crackers and used for malicious purposes like identity theft and online fraud – with the US (24.6 per cent) and China (7.8 per cent) in second and third place. The statistics, taken from Symantec’s Global Internet Threat Report for the period July to December 2004, are based on the number of PCs worldwide that are known to be infected with bot agents, such as the infamous Agobot worm.

The prevalence of botnets has become a key issue in information security over recent months. Botnets are computers which are infected by worms or Trojans and taken over surreptitiously by hackers and brought into networks to send spam, more viruses, or launch denial of service attacks.

Worst offender

In the first half of 2004, Finland had the highest level of bot infection. This time around it doesn't even chart. Nigel Beighton, Symantec’s Director of Enterprise Strategy, EMEA, blames Britain's pre-eminence in the latest chart to the rapid roll-out of broadband in this country. "We saw 93 per cent growth in broadband connections last year and this has had a huge impact on the number of people accessing the Internet. Unfortunately, new broadband users may not be fully aware of the additional safety precautions that need to be taken when using an always-on high-speed Internet connection. Clearly, awareness around security issues is improving and it’s making a notable difference, but education still remains the number one challenge," he said

The number of bot-infected computers declined from 30,000+ a day in July to an average of less than 5,000 a day by December, according to Symantec. Although in absolute terms the size of botnet might be decreasing the severity and risks associated with them continue to be a major problem mainly because of a noticeable shift towards the use of bots and bot networks for financial gain.

A recent study by the Honeynet Project suggested zombie controllers were running smaller botnets and limiting the chat they generate in order to try to escape detection. Symantec's Beighton rejects this theory. "I don't think the bad guys are changing how they operate, it's just that they are less successful in obtaining bots," he said.

Agobot - one of the most common agents for compromising Windows PCs - can spread by exploiting the well-known LSASS vulnerability in Windows also exploited by the Sasser worm. Beighton reckons the use of the free firewall in XP SP2 has helped curtail the rise of botnets but he said greater user awareness is a greater factor in helping to clean up the net. ®